Usually, traditional electronic billboards, smart cards, and electronic identifiers display specific images to convey certain information by using liquid crystal displays (LCDs). However, the smart cards and the electronic identifiers, using the liquid crystal displays, are not only power-hungry but also inflexible, causing various restrictions and inconvenience in use. Furthermore, the traditional electronic billboards, using the liquid crystal displays, are also power-hungry, and the images displayed under sunlight cannot be clearly identified.